The present invention is related to the sensing of analytes in a medium or a vacuum, such as odors, smells, vapors and the like in air, and in particular, to systems and methods of determining, resolving, or identifying such analytes once detected.
One approach for sensing analytes is the use of an array of sensors on a substrate. Each sensor has a characteristic response to exposure to an analyte, such as an odor. The sensors can be connected to an electrical circuit for measuring the responses to the analyte. See, for example, U.S. patent application Ser. No. 09/130,775, filed Aug. 7, 1998 and assigned to the present assignee, which is incorporated by reference herein. Each sensor responds to a broad class of stimuli, with the collective response of the many different members of the sensor array providing a fingerprint of an analyte of interest.
Typically, each array contains sensors with varying compositions, each of which responds to certain properties of the analytes. The array is exposed to a panel of known analytes and pattern recognition algorithms are used to analyze the responses and to produce a fingerprint of the responses of known analytes (this data is called a training set). Next, the array is exposed to an unknown analyte and this response pattern is matched with that of the patterns from the training set to identify the unknown analyte. However, equal weighting of responses from all sensors in a particular array can be problematic. In practice, not all measurable properties of an analyte are useful for analyte identification. While certain characteristics vary widely between different analytes, other characteristics are very similar between analytes.
Thus there is a need for systems and methods that give greater weight to sensors that measure properties which are clearly distinguishable between two analytes. There is also a need for systems and methods that give greater weight to sensors which can reproducibly measure a particular property. Such systems and methods will enhance the ability of a sensor array to correctly identify analytes, as well as prolong the predictive capability of a training set by reducing the deleterious effects of sensor drift. This invention fulfills this and other needs.